Class BeanToPropertyValueTransformer

java.lang.Object
org.apache.commons.beanutils.BeanToPropertyValueTransformer
All Implemented Interfaces:
org.apache.commons.collections.Transformer
public class BeanToPropertyValueTransformer extends Object implements org.apache.commons.collections.Transformer

Transformer that outputs a property value.

An implementation of org.apache.commons.collections.Transformer that transforms the object provided by returning the value of a specified property of the object. The constructor for BeanToPropertyValueTransformer requires the name of the property that will be used in the transformation. The property can be a simple, nested, indexed, or mapped property as defined by org.apache.commons.beanutils.PropertyUtils. If any object in the property path specified by propertyName is null then the outcome is based on the value of the ignoreNull attribute.

A typical usage might look like: 

// create the transformer
BeanToPropertyValueTransformer transformer = new BeanToPropertyValueTransformer( "person.address.city" );

// transform the Collection
Collection peoplesCities = CollectionUtils.collect( peopleCollection, transformer );

This would take a Collection of person objects and return a Collection of objects which represents the cities in which each person lived. Assuming...

  • The top level object in the peeopleCollection is an object which represents a person.
  • The person object has a getAddress() method which returns an object which represents a person's address.
  • The address object has a getCity() method which returns an object which represents the city in which a person lives.
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private final boolean
    ignoreNull
    Should null objects on the property path throw an IllegalArgumentException?
    private final org.apache.commons.logging.Log
    log
    For logging.
    private final String
    propertyName
    The name of the property that will be used in the transformation of the object.

  • Constructor Summary

    Constructors
    Constructor
    Description
    BeanToPropertyValueTransformer(String propertyName)
    Constructs a Transformer which does not ignore nulls.
    BeanToPropertyValueTransformer(String propertyName, boolean ignoreNull)
    Constructs a Transformer and sets ignoreNull.

  • Method Summary

    Modifier and Type
    Method
    Description
    String
    getPropertyName()
    Returns the name of the property that will be used in the transformation of the bean.
    boolean
    isIgnoreNull()
    Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
    Object
    transform(Object object)
    Returns the value of the property named in the transformer's constructor for the object provided.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • log

      private final org.apache.commons.logging.Log log
      For logging.

    • propertyName

      private final String propertyName
      The name of the property that will be used in the transformation of the object.

    • ignoreNull

      private final boolean ignoreNull

      Should null objects on the property path throw an IllegalArgumentException?

      Determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.

  • Constructor Details

    • BeanToPropertyValueTransformer

      public BeanToPropertyValueTransformer(String propertyName)
      Constructs a Transformer which does not ignore nulls. Constructor which takes the name of the property that will be used in the transformation and assumes ignoreNull to be false.
      Parameters:
      propertyName - The name of the property that will be used in the transformation.
      Throws:
      IllegalArgumentException - If the propertyName is null or empty.

    • BeanToPropertyValueTransformer

      public BeanToPropertyValueTransformer(String propertyName, boolean ignoreNull)
      Constructs a Transformer and sets ignoreNull. Constructor which takes the name of the property that will be used in the transformation and a boolean which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
      Parameters:
      propertyName - The name of the property that will be used in the transformation.
      ignoreNull - Determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
      Throws:
      IllegalArgumentException - If the propertyName is null or empty.

  • Method Details

    • getPropertyName

      public String getPropertyName()
      Returns the name of the property that will be used in the transformation of the bean.
      Returns:
      The name of the property that will be used in the transformation of the bean.

    • isIgnoreNull

      public boolean isIgnoreNull()
      Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.
      Returns:
      The flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

    • transform

      public Object transform(Object object)
      Returns the value of the property named in the transformer's constructor for the object provided. If any object in the property path leading up to the target property is null then the outcome will be based on the value of the ignoreNull attribute. By default, ignoreNull is false and would result in an IllegalArgumentException if an object in the property path leading up to the target property is null.
      Specified by:
      transform in interface org.apache.commons.collections.Transformer
      Parameters:
      object - The object to be transformed.
      Returns:
      The value of the property named in the transformer's constructor for the object provided.
      Throws:
      IllegalArgumentException - If an IllegalAccessException, InvocationTargetException, or NoSuchMethodException is thrown when trying to access the property specified on the object provided. Or if an object in the property path provided is null and ignoreNull is set to false.